GLOSSY AND TRANSPARENT INK-PRINTABLE POLYOLEFINIC FILM COMPOSITION

Abstract: Ink-printable films (10) comprising at least one outer ink-printable layer (11) consisting essentially of a polyolefin material containing a polymeric resin additive which enhances the ink printability property of the layer while not altering the optical properties of the film.

Description: GLOSSY AND TRANSPARENT INK-PRINTABLE POLYOLEFINIC FILM COMPOSITION Background of the Invention This invention relates to polyolefinic polymer compositions having improved ■ proDerties In particular, this invention relates to improving the receptivity or adhesion of printing inks to the surface of shaped articles made from such polyolefinic polymer compositions Polyolefinic polymers, in particular ethylene polymers such as polyethylene are used for forming shaped articles such as sheets, films, tubes, bottles, containers, etc therefrom However, polyethylene has, and consequently articles made thereof have, an extremely smooth hydrophobic surface which is unreceptive to most common types of printing inks and dyes and thus it is difficult to print the surface of polyethylene articles. Various known methods have been used to make ethylene polymers more receptive to printing inks. For example, there are a number of surface treating tecnniques which have been developed to improve the receptivity of the polymer surface to printing inks including chemical treatment with oxidizing agents such as chlorine and strong acids and electronic, or corona discharge treatment of the polymer surface. Flame treatment of the surface of polyethylene has also been used to make the polyethylene more receptive to printing inks. Another method used to improve the receptivity of the polymer surface to printing inks is to apply a coating or printable top layer on the surface of the polymer layer to be printed. For example, multilayer films have been disclosed in the prior art wherein the top printable layer or printable skin layer of the film is described as being made from materials such as ethylene acrylic acid, ethylene methyl acrylic acid, ethylene ethyl acryiate, ethylene methyl acryiate, acrylonitrile butadiene styrene, nylon, polybutyiene, polystyrene, polyurethane, poiysulfone, polyvinylidene chloride, polypropylene, polycarbonate, polymethyl pentene, styrene maleic anhydride, styrene acrylonitrile, ionomers based on sodium or zinc salts of ethylene/methacrylic acid, acrylics, cellulosics, fluoroplastics, nitriles and thermoplastic polyesters. Still another method used to improve the receptivity of a polymer surface to printing inks is to form a novel polymeric composition which has as one of its improved properties an enhanced receptivity to printing ink. Thus, articles, such as a monolayer film, made from said composition would have the improved property of enhanced receptivity to printing ink. For example, it is known to obtain an ethylene poiymer composition having excellent receptivity to printing inks after surface treatment by incorporating in the ethylene poiymer an N-substituted unsaturated carboxylic amide, it is also known to biend together a mixture of commercially available, high molecular weight polyethylene with a minor but effective amount of an oxidized, low molecular weight, polyethylene wax to form a plastic molding composition and shaping the composition into an article by any of the known commerαar methods, which article has a surface which is hydrophilic and receptive to printing inks. Furthermore, polyolefin compositions having improved adhesion to water based inks have been made by incorporating into the polyolefin an effective amount of a lactamide. . It is desired to provide yet another novel polymeric composition having enhanced receptivity to printing ink by blending together an ethylene poiymer with an effective amount of an ink pπntabiiity enhancing agent. An object of the present invention is to impart the desired pπntability and adhesion to printing inks to polyolefin compositions without adversely affecting the optical properties of the polyolefin Summary of the Invention One aspect of the present invention is directed to a composition which can be used to make a film that combines excellent pnntability with excellent optical properties. The composition is obtained by blending into a polyolefin a minor portion of a polymeric additive which does not deteriorate the optical properties of the polyolefin. The composition of the present invention includes a polyolefin material with a polymeric additive having double bonds or having double bonds and a polystyrene present in its chemical structure; or an anhydride modified polyolefin. Another aspect of the present invention is directed to a film made of the above composition. Still another aspect of the present invention is preparing a film including the steps of (a) forming the composition; (b) making a film from the composition; and (c) applying an electrical discharge treatment to at least one of the surfaces of the film. Brief Description of the Drawings Figure 1 is an enlarged partial cross-sectional view of one embodiment of a film structure of the present invention. Figure 2 is an enlarged partial cross-sectional view of another embodiment of a film structure of the present invention. Figure 3 is an enlarged partial cross-sectional view of one embodiment of a pressure-sensitive adhesive film structure useful for making labels in accordance with the present invention. Figure 4 is an enlarged partial cross-sectional view of another embodiment of a pressure-sensitive adhesive film structure useful for making labels in accordance with the present invention. Detailed Description of the Preferred Embodiments In its broadest scope the composition of the present invention includes a polyolefinic polymer and a polymeric additive referred to herein as an "ink printability enhancer" ("IPE"). The polyolefinic polymer includes for example low-density polyethylene (LDPc), linear low density polyethylene (LLDPE), medium density polyethylene (MDPE), a high-density polyethylene (HDPE), polypropylene (PP), propylene-ethylene copolymers, or mixtures of such materials or mixtures which contain such materials. To the polyolefinic polymer material is added the IPE polymeric additive. The IPE is selected from a material which, in general, contains double bonds or double bonds and a polystyrene in the IPE's chemical structure or an anhydride modified polyolefin. Also, the IPE should not adversely affect the optical properties of composition. For example, the IPE should not increase haze by more than 5 percent (absolute units) as measured according to ASTM D-1003 and/or should not decrease the 60 degree gloss by more than 5 percent (absolute units) as measured according to ASTM D-2457. Preferably, the IPE is selected from the group comprising styrenic block copolymers, modified polyolefins and polyolefin polymers containing some degree of unsaturation or mixtures thereof. The styrenic block copolymers used as the IPE in the present invention include, for example, styrene-isoprene-styrene (SIS), styrene-butadiene-styrene (SBS) of a grade having lower than 40 weight percent styrene, styrene-ethylene-butylene-styrene (SEBS), styrene-isoprene (SI), SIS/styrene-isoprene blend compositions and mixtures thereof. The polymeric polyolefins using some degree of unsaturation include, for example, polybutadiene, ethylene-propylene-diene copolymers (EPDM), polyϊsoprene, transpolyoctenamer and mixtures thereof. The modified poiyolefins include, for example, anhydride modified polyethylenes such as maleic anhydride containing olefin polymers and copolymers such as those polymers commercially available under the trademark ADMER ® (trademark of Mitsui Petrochemicals) and styrene maleic anhydride and mixtures thereof. The preferred IPE used in the present invention is SIS or mixtures containing SIS. In the composition, the IPE is present in an amount of from 3 weight percent to 50 weight percent, preferably from 5 weight percent to 30 weight percent; and more preferably from 7 weight percent to 25 weight percent, with the remainder of the composition being the polyolefinic polymer, that is, the composition generally contains from 50 weight percent to 97 weight percent, preferably from 70 weight percent to 95 weight percent; and more preferably from 75 weight percent to 93 weight percent polyolef i n. Other additives can also be blended into the composition. Other optional additives that can be added to the composition of the present invention include for example, antioxidants, antiblocks, antistatic additives, processing aids, inorganic fillers, UV stabilizers, slip additives and pigments. The amount of optional additive that can be used in the present composition will vary depending on the properties desired and effect desired Usually one or more optional additives may be present in the composition in an amount of from 0 001 weight percent to 15 weight percent for each additive individually For example, when a nucleator or clarifying agent is used, the composition can include from 0 1 to 0 5 weight percent of the nucleator or clarifying agent If, for example, a lower gloss property is desired but still maintaining ink printability, a filler such as calcium carbonate, talcum, silicon dioxide, chalk or other filler may be used, and the amount can be from 1 to 6 weight percent If, for example, transparency is not desired, a pigment may be used in an amount of from 0 1 weight percent to 15 weight percent and still maintain the property of ink printability Processing aids that may be blended in the composition may include, for example, Viton ® from Du Pont, Dynamar 0 from 3M or Ucarsil ® PA from Union Carbide which are all preferably added below 1 weight percent The polyolefin, IPE and other optional additives can be blended by well known techniques into the art such as by tumble blending or separately feeding into an extruder hopper The composition of the present invention can be used to make several forms, including, for example, film, sheet or shaped articles by known processes. For making shaped articles, the processes include, for example, blow molding, compression molding, and injection molding For sheet and film manufacture, extrusion processes such as cast or blow processes may be used In Modern Plastics Encyclopedia, 1969-70 edition, sheet is defined (page 52C) as a flat section of a thermoplastic resin with the length considerably greater than the width and 10 mils or greater in thickness Film is defined (page 43) as an optional term for sheet having a nominal thickness not greater than 0 010 inches. As an illustration of the present invention, a monolayer film and a multilayer film product wiil be described herein below using the composition of the present invention A monolayer fiim can be made by various conventional film forming processes including for example, a cast film process, a blown film process, oriented film process and other extrusion processes or coating processes. A multilayer film may be made by processes commonly used for manufacturing a multilayer film including, for example, coextrusion, extrusion-coating, calendering and lamination. For making a multilayer film, coextrusion is preferred, because then the multilayer film product can be obtained in one step While the composition of the present invention can be used to make a monolayer film, the present invention will be described herein with reference to a multilayer film, a preferred embodiment of the present invention In its broadest scope the multilayer film comprises a coextruded film structure containing at least one of its external or outer layers made of the composition of the present invention Any film structure such as A B, A B/A or A/B/C layered structures is possible, provided that at least one of the outer layers or skin layers of the multilayer film is made of the present composition In Figure 1 , there is shown a two-layer film 10, comprising an outer layer 1 1 made of the blend composition of the present invention and an inner adjacent layer 12 of one or more polymers Layer 12 can be made of any polymer resin which will adhere to the outer layer 1 1 including, for example, EVA, EAA, EMA, EMAA, EBA, lonomers, modified polyolefins, and polyolefin materials such as LDPE, MDPE, HDPE, LLDPE, PP or blends thereof One of the advantages of using the composition of the present invention as one of the layers in a film structure (layer 1 1 in Figure 1 ), is the recydability of the layer Any regπnd, scrap or unused excess material can be reprocessed by reintroducing the material, as recycle, back into the layer made of the present composition or back into another layer of the film without significantly affecting the properties of the film When recycle material is used, generally from one percent by weight to 50 percent by weight of the recycle material can be added back into the layer With reference to Figure 2, there is shown one preferred embodiment of a multilayer film structure 20 of the present invention, in this case a three-layer structure, including two outer layers or skin layers 21 with a core layer 22 sandwiched between the two skin layers 21 The skin layers 21 are made of the aforementioned composition of the present invention The core layer 22 can be made of any of the same resins for iayer 1 1 and preferably a polyolefin material such as LDPE, MDPE, HDPE, LLDPE, PP or blends thereof Also, any of the aforementioned optional additives used for the com position of layer 11 can be used in any of the other layers 12 or 21 of the film The overall thickness of the film of the present invention can be from 5 microns to 200 microns, preferably from 50 to 150 microns Preferably, the skin layer is from 2 percent to 25 percent of the total thickness of the film, preferably from 5 percent to 20 percent of the total thickness of the film Optionally, at least one of the surfaces of the film, intended to be printed, is treated by a corona discharge treatment to bring the film's surface tension above 40 milli newton per meter (mN/m), preferably above 50 mN/m as measured according to ASTM D-2578 The corona discharge treatment is applied to at least one surface of the film The corona discharge treatment is well known in the art and described for example in surface properties and testing, Plastics & Polymers, April 1969, pages 138-142 While corona treatment, alone, increases the surface tension of the film layer treated to improve the spreading of the ink on the film surface, it is believed that the composition of the present invention, in conjunction with corona treatment or any other surface treatment of the film, further advantageously enhances the adhesion of the ink on the film without significant loss of optical properties of In accordance with another embodiment of the present invention, the monolayer or multilayer films can be used as stock material for manufacturing labels, signs, displays, tags, posters, stickers. For example, the film label stock can be used for making in-mold labels, pressure-sensitive labels and wrap around labels, sleeves and shrink sleeves. One embodiment of this invention of particular interest relates to polyolefinic fiims useful for making glossy, or glossy and transparent, and ink-printable pressure-sensitive labels. The clear polyolefinic films made of medium to high density polyethylene fiim and . pressure-sensitive labels made from polyethylene film are typically used in labeling bottles. While it is known to produce labels of polyolefins films, as aforementioned, the poor printability of the polyolefin film usually requires the application of an ink-printable layer on top of the polyolefin film to impart improved printability to the polyolefin film. Multilayered label films are commonly produced by coating a polyolefin film with an ink-printable acrylic polymer, or coextruding or laminating the polyolefin film with a iayer of ink-printable polymer. The composition of the present invention can be used to produce in one step polymeric films based on olef inic poiymers without use of a top coat or ink printable layer. A monolayer film made from the present composition provides excellent printability without a significant loss of other film properties such as optical properties such as low haze and high gloss. While a monolayer film can be produced from the composition of the present invention, for economical reasons, a preferred embodiment of the present invention is to make a multilayer film wherein one of the outer layers or skin layers of the film is made of the composition of the present invention. A pressure-sensitive film stock 30 is illustrated in Figure 3 which includes a single skin iayer 11 on the outer side of a core layer 12 and a pressure-sensitive adhesive iayer 31 directly adjacent the inner side of the core layer 12. The pressure-sensitive adhesive used for layer 31 may be any conventional pressure-sensitive adhesive such as acylic and styrene butadiene. The fiim stock 30 is preferably used for the manufacture of pressure-sensitive labels. Figure 4 shows another embodiment of a multilayer pressure-sensitive film stock 40 including two skin layers 21 with a core layer 22 and an adhesive layer 31 attached to at least one of the skin layers 21. In carrying out the process for making the film of the present invention, generally, first a film composition is formed wherein the composition comprises at least one polyolefin material and at least one polymeric additive which enhances the ink printability property of the composition while not adversely affecting the optical properties of the composition. Then, a film from the composition is formed, for example, by coextrusion techniques. An electrical discharge treatment may be applied to at least one surface of the resultant film to raise the surface tension of the resultant film. As aforementioned, with the use of a skin layer utilizing the composition of the present invention, the ink printability of a multilayer film is enhanced. The skin layer of the multilayer film can be printed with various printing systems. For example, print techniques useful herein, include silk screen printing, rotogravure, letter press, offset, flexographic printing, stipple printing, cold fixing laser printing, copperplate printing. Various types of inks can also be selected for use in the present invention including, for example, one and two component inks, oxidativeiy or UV-drying inks, dissolved or dispersed or 100% ink systems. Many combinations of film/printing, ink/printing techniques are possible. General Procedure In the Examples which follow, the general procedure used to manufacture the film of the present invention is as follows: Charge "I" of a film forming resin is prepared comprising X weight percent of a polymeric resin referred to below as "Resin A", Y percent of a polymeric additive referred to below as "Additive B" and Z percent of one or more polyolefin resins referred to below as "Resin Composition C". Then Charge "II" of a film forming resin composition comprising one or more polyolefin resins is prepared. Both the "I" and "II" Charges are fed into extruders and coextruded to form a three-layered film with a l/ll/l layer structure. The total thickness of the film structure is T and the thickness of each layer of Charge I is T1. An electrical "corona" discharge treatment is applied on one or both surfaces of the film to raise its surface tension. The resulting film has excellent optical properties (similar haze and gloss as films consisting essentially of polyolefin), and has excellent ink-printability without the need to add any substrate onto the film's surface. For economical or practical reasons, it is preferable to produce a multilayer film with the Charge i being at least one of the skin layers, but monolayer films comprising only the Charge I can also be made. The following compositions and conditions were tested. Example 1 A coextruded three-layer film having a l/ll/l layer structure was manufactured according to the above General Procedure. Charge I included Resin A, Additive B and Resin Composition C. Resin A was 7 weight percent of a styrene-isoprene-styrene copolymer (SIS) having a melt index (Ml) of 9.0 grams per 10 minutes (g/10 min) (200 degrees centigrade (0°)/5 kilograms (kg)) and containing 85 weight percent of polymerized isoprene. Additive B was 5 weight percent of a 15 weight percent silicon dioxide masterbatch in a low density polyethylene (LDPE). Resin Composition C was 10 weight percent of a high density polyethylene (HDPE) having a density of 0 955 gram per cubic centimeter (g/crτr) and a Ml of 4 0 g/10 mm (190°C/2 16 g) The balance to 100 percent for Charge i was a LDPE having a density of 0 921 g/cm 3 and a Ml of 3 5 g/10 mιn (190°C 2 16 kg) Charge II of the film structure comprised 80 weight percent of a HDPE having a density of 0 955 g/cm 3 and a Ml of 4 0 g/10 mm (190°C/2 16 kg), and 20 weight percent of a LDPE having a density of 0 923 g/cm 3 and a Ml of 1 75 g/10 mm (190°C 2 16 kg) A film having a of thickness of 90 micrometers of a l/ll/l layer structure was produced by a cast coextrusion process using Charges I and II described above The thicknesses (T1) of the external layers (Charge I) was 10 micrometers each One surface of the film was treated by a "corona" discharge treatment to bring its surface tension above 50 mN/m. The optical properties of the film is shown in Table I The percent gloss measurement of the film was measured in accordance with ASTM D-2457 and the percent haze measurement was measured in accordance with ASTM D-1003. The fiim produced in this Example 1 was printed on the corona treated side using UV curable inks on flat bed silk screen printing equipment. The ad hesi on of the i nk on the f i I m was tested usi ng the f ol I owi ng f ou r i nk adhesion tests- (1 ) adhesive tape test, (2) scratch resistance on the dry film, (3) scratch resistance after immersion of the film for 4 hours in a 50/50 volume percent solution of water plus shampoo at room temperature (22°C), and (4) scratch resistance after immersion of the films for 22 hours in a 50/50 volume percent solution of water plus shampoo at room temperature (22°C). The aforementioned adhesive tape test is described as follows: -A 15 mm wide piece of self adhesi e tape is pressed onto the surface of the printed area of a film sample. This is then rapidly pulled away from the film The percentage of ink removed from the sample by the tape is compared The amount of ink is visually compared and a numerical rating of " 1 " to "4" is given to the film samples wherein " 1 " is the lowest amount of ink remaining on the tape and "4" being the greatest amount of ink remaining on the tape. The aforementioned scratch resistance test is described as follows: A film label sample is adhered onto a stiff surface. The printed surface of the film is manually rubbed with a metal spatula The difficulty or ease of scratching the ink is rated as follows: " 1 " not scratchable, "2" scratchable with difficulty, "3" scratchable, "4" easily scratchable, "5" scratchable by touching. This test is performed on the dry film or on the wet film after immersion in the solutions described above The results of the above ink adhesion tests are listed in Table II Example 2 A three-layer coextruded film having a l/ll/l layer structure was manufactured ' -nd tested following the procedure of Example 1 The Charges 1 and II were the same as in Example 1 except that Resin A was 14 weight percent SIS having a of 9 0 g/10 rπιn (200° 5 kg) and containing 85 weight percent of polymerized isoprene The optical properties of the resultant fiim are shown in Table I and the results of the adhesion tests are listed in Table II. Example 3 A three-layer coextruded film having a l/ll/l layer structure was manufactured and tested following the procedure of Example 1. The Charges I and II were the same as m Example 1 except that Resin A was 25 weight percent Admer ® L 2000 resin, a polymeric resin containing around 0.6 weight percent of grafted maleic anhydride and commercially available from Mitsui Petrochemicals. The optical properties of the resultant film are shown in Table I and the results of the adhesion tests are listed in Table II. Comparative Example A A three-layer coextruded film having a l/ll/l layer structure was manufactured and tested following the procedure of Example 1. The Charges I and II were the same as in Example 1 exceptthat no Resin A was used in this Example. This comparative example was used as the Control. The optical properties of the Control is shown in Table I and the results of the adhesion tests are listed in Table II. Comparative Example B The adhesion tests described in Example 1 were earned out on a pure polyethylene film coated with an acrylic coating (Comparative Example B). The results are listed in Table II. TABLE I 60 Degree Gloss Haze Film (%) (%) Control 80 18 (Comparative Example A) Example 1 85 19 Example 2 85 17.5 Example 3 81 18 TABLE II Control PE Top Coat (Comparative (Comparative Example A) Example 1 Example 2 Example 3 Example B) Tape test (1) 4 3 2 1 2 Dry scratch^ 2 ' 4 1 2 1 1 Wet scratch 4 hours^ 2 ^ 4 2 2 3 2 Wet scratch 22 hours (2) 4 2 2 4 2 TOTAL 16 8 8 9 7 ( ^Tape Test Ratings: 1 = lowest amount of ink on the tape o 4 = greatest amount of ink on the tape I (2) Scratch Test Ratings: 1 = not scratchable 2 = scratchable with difficulty 3 = scratchable 4 = easily scratchable 5 = scratchable by touching Table I shows that the optical properties of Examples 1 , 2 and 3 are similar to that of the Control film. From the results shown in Table II, films from Examples 1 , 2 and 3 perform as well as the film of Comparative Example B, and far better than the Control film. Example 4 A three-layer coextruded film having a l/ll/l layer structure was manufactured according to the above General Procedure. Charge I included components Resin A, Additive B and Resin Composition C. Resin A was 12 weight percent of SIS having a Ml of 9.0 g/10 min (200°C/5 kg) and containing 85 weight percent of polymerized isoprene. Additive B was 5 weight percent of a 15 weight percent silicon dioxide masterbatch in a LDPE. Resin Composition C was 10 weight percent of a HDPE having a density of 0.965 g/cm 3 and a Ml of 8.0 g/10 min (190°C/2.16 kg). The balance to 100 percent for Charge I was a LDPE having density of 0.923 g/cm 3 and a Ml of 1.75 g/10 min (190°C/2.16 kg). Charge II of the film structure comprised 70 weight percent of a HDPE having a density 0.965 g/cm 3 and a Ml of 8.0 g/10 min (190°C/2.16 kg); and 20 weight percent of a LDPE having a density of 0.922 g/cm 3 and a Ml of 1.2 g/10 min (190°Q2.16 kg). A film having a thickness of 90 micrometers of a l/ll/l layer structure was produced by a cast coextrusi on process usi ng Charges I and It descri bed above. The thicknesses (T ) of the external layers (Charge I) was 10 micrometers each. One surface of the film was treated by a "corona" discharge treatment to bring its surface tension above 50 mN/m. The optical properties of the film are shown on the following Table III. The percent gloss measurement of the film was measured in accordance with ASTM D-2457 and the percent haze measurement was measured in accordance with ASTM D-1003. Example 5 A three-layer coextruded film having a l/ll/l layer structure was manufactured and tested following the procedure of Example 4. The Charges I and II were the same as in Example 4 except that there was no Additive B in Charge I. The optical properties of the resultant film are shown in Table III. Example 6 A three-layer coextruded film having a l/ll/l layer structure was manufactured and tested following the procedure of Example 4. The Charges I and II were the same as in Example 4 except that Resin A was 12 weight percent of a styrene-isoprene-styrene/styrene-isoprene copolymers blend (SIS/SI) having a Ml of 10.0 g/10 min (200°C/5 kg) and containing 85 weight percent of polymerized isoprene. The SIS/SI ratio of the blend was 82/18 percent. The optical properties of the resultant film are shown in Table ill. Example 7 A three-layer coextruded film having a l/ll/l layer structure was manufactured and tested following the procedure of Example 4. The Charges I ana II were the same as in Exari.μie 4 except that Resin A was 12 weight percent of. SIS having a Ml of 12.0 g/10 min (200°C5 kg) and containing 82 weight percent of polymerized isoprene. The optical properties of the resultant film are shown in Table III. Example 8 A three-layer coextruded film having a l/ll/l layer structure was manufactured and tested following the procedure of Example 4. The Charges I and II were the same as in Example 4 except that Resin A was 12 weight percent of SIS having a Ml of 13.0 g/10 min (200°C 5 kg) and containing 70 weight percent of polymerized isoprene. The optical properties of the resultant film are shown in Table III. Example 9 A three-layer coextruded film having a l/ll/l layer structure was manufactured and tested following the procedure of Example 4. The Charges I and II were the same as in Example 4 except that Resin A was 12 weight percent of SIS having a Ml of 40.0 g/10 min (200O5 kg) and containing 55 weight percent of polymerized isoprene. The optical properties of the resultant film are shown in Table III. Comparative Example C A three-layer coextruαed film naving a l/ll/l layer structure was manufactured and tested following the procedure of Example 4 The Charges I and II were the same as in Example 4 except that no Resin A was used in Charge I This comparative example was used as the Control The optical properties of the Control are shown in Table 111 TABLE III 60 Degree Gloss Haze Film (%) (%) Control 79 25 (Comparative Example C) Example 4 83 22 Example 5 91 18 Example 6 85 20 Example 7 85 20 Example 8 85 21 Example 9 95 22 Table III shows that the optical properties of Examples 4-9 are simiiarto the Control. Comparative Example D A three-layer coextruded film having a l/ll/l layer structure was manufactured according to the above General Procedure. Charge I included components Resin A, Additive B and Resin Composition C. Resin A was 8 weignt percent of a sytrene-butadiene-styrene copolymer (SBS) having a Ml of 6.0 g/10 mm (200°C/5 kg) and containing 60 weight percent of polymerized butadiene. Additive B was 5 weight percent of a 15 weight percent silicon dioxide masterbatch in a LDPE. Resin Composition C was 10 weight percent of a HDPE having a density of 0.955 g/cm 3 and a Ml of 4.0 g/10 min (190°C/2.16 kg). The balance to 100 percent for Charge I was a LDPE having density of 0.921 g/cm 3 and a Ml of 3.5 g/10 min (190°C/2.16 kg). Charge II of the fiim structure comprised 80 weight percent of a HDPE having a density 0.955 g/cm 3 and a Ml of 4.0 g/10 min ( 190°C/2.16 kg); and 20 weight percent of a LDPE having a density of 0.923 g/cm 3 and a Ml of 1.75 g/10 mm (190°C/2.16 kg). A film having a thickness of 90 micrometers of a l/ll/l layer structure was produced by a cast coextrusion process using Charges 1 and II descrioed above. The thicknesses (T1 ) of the external layers (Charge I) was 10 micrometers each. One surface of the film was treated by a "corona" discharge treatment to bring its surface tension above 50 mN/m. The optical properties of the film is shown on the following Table IV. The percent gloss measurement of the film was measured in accordance with ASTM D-2457 and the percent haze measurement was measured in accordance with ASTM D- 1003. Comparative Example E A three-layer coextruded film having a l/ll/l layer structure was manufactured and tested following the procedure of Example 10. The Charges I and II were the same as in Example 10 except that Resin A was 25 weight percent of a ethylene-acrylic acid copolymer (EAA) having a Ml of 10.0 g/10 min (190°C/2.16 kg) and containing 9 weight percent of polymerized acrylic acid. The optical properties of the resultant film are shown in Table IV. Comparative Example F A three-layer coextruded film having a l/ll/l layer structure was manufactured and tested following the procedure of Example 10. The Charges I and II were the same as in Example 10 except that Resin A was 25 weight percent of a ethylene-methyl acryiate copolymer (EMA) having a Ml of 3.0 g/10 min (190°C/2.16 kg) and containing 15 weight percent of polymerized methyl acryiate. The optical properties of the resultant film are shown in Table IV. Comparative Example G A three-layer coextruded film having a l/ll/l layer structure was manufactured and tested following the procedure of Example 10. The Charges I and II were the same as in Example 10 except that Resin A was 25 weight percent of a ethylene-butyl acryiate copolymer (EBA) having a Ml of 4.0 g/10 min (190°G2.16 kg) and containing 17 weight percent of polymerized methyl acryiate. The optical properties of the resultant film are shown in Table IV. Comparative Example H A three-iayer coextruded film having a l/ll/l layer structure was manufactured and tested following the procedure of Example 10. The Charges I and II were the same as in Example 10 except that Resin A was 25 weight percent of a sodium salt of an ethylene- methacryhc acid copoiymer having a Ml of 2.8 g/10 mm (190°C 2.16 kg) and having a density of 0.94 g/cm Ξ . The optical properties of the resultant film are shown in Table IV. Comparative Example I A three-layer coextruded film having a l/ll/l layer structure was manufactured and tested following the procedure of Example 10. The Charges I and II were the same as in o Example 10 except that Resin A was 15 weight percent of a butyl rubber. The optical properties of the resultant film are shown in Table IV. Comparative Example J A three-layer coextruded film having a l/ll/l layer structure was manufactured and tested following the procedure of Example 10. The Charges I and II were the same as in 5 Example 10 except that no Resin A was used in Charge I. This comparative example was used as the Control. The optical properties of the Control are shown in Table IV. TABLE IV Film 60 Degree Gloss , Haze 0 (%) (%) Control 80 18 (Comparative Example J) Example D 33 42 Example E 72 24 5 Example F 62 24 Example G 70 20 Example H 65 29 Example I 17 66 0 5 Table IV shows that the optical properties of Comparative Examples D-1 are worse (have lower gloss and higher haze) than the Control film J.

Claims: WHAT IS CLAIMED IS: 1. A fiim comprising at least one outer ink-printable layer, said layer consisting essentially of at least one polyolefin material and at least one polymeric additive which enhances the ink-printability property of said layer while not adversely affecting the optical properties of the film. . '■ 2. A film of Claim 1 further comprising a pressure-sensitive adhesive iayer. 3. A label made from the film of Claim 1. 4. A pressure sensitive label made from the film of Claim 2. 5. The film of Claim 1 , wherein the polymeric additive is an olefinic polymer or copolymer having double bonds or double bonds and polystyrene in its chemical structure. 6. The film of Claim 1 , wherein the polymeric additive comprises a material selected from the group consisting of styrenic block copolymers, modified polyolefins and polyolefin polymers containing some degree of unsaturation. 7. The film of Claim 1 , wherein the polymeric additive is a styrenic block copolymer. 8. The film of Claim 7, wherein the styrenic block copolymer is styrene- isoprene-styrene or styrene-isoprene. 9. The film of Claim 1 , wherein the polyolefin material is an ethylene polymer. 10. The film of Claim 1 , wherein the polyolefin material is selected from group consisting of LDPE, MDPE, LLDPE, HDPE, PP, propylene-ethylene copolymers, and mixtures thereof. 11. The fiim of Claim 1 , wherein polymeric additive is present in an amount of from 3 weight percent to 50 weight percent. 12. The film of Claim 1 , wherein polymeric additive is present in an amount of from 5 weight percent to 30 weight percent. 13. A method of making a label comprising the steps of: i) providing a film comprising at least one outer ink-printable layer, said layer consisting essentially of at least one polyolefin material and at least one polymeric additive which enhances the ink-printability property of said layer while not adversely affecting the optical properties of the film; and ii) printing on said outer ink-printable iayer.

Inventors: REGNIER FRANCOIS JACQUES FREDE, REGNIER, FRANCOIS, JACQUES, FREDERIC
Applicants: DOW CHEMICAL CO, THE DOW CHEMICAL COMPANY
Application year: 1994
Main classification: C08L23
IPC codes: B32B27, C08J5, C08L23, C08L53, C08L101, G09F3